2010 Trans Fats Update

Every once in awhile I check in with the trans fats research, to see if they are living up to their bad reputation.

Some background:

Fats contain long chains of carbon molecules. Each carbon molecule has positions (or bonds) at which a hydrogen can be attached. If all the potential hydrogen bonds on all the carbons are filled, the fat is saturated. Monounsaturated fats have one open bond, while polyunsaturated fats have two or more. The more open bonds, the less stable (and more liquid) a fat is.

Hydrogenation is the process of adding hydrogen molecules to an unsaturated fat’s open bonds. If you take a batch of unsaturated fats and add hydrogen molecules to much of it, it will make the batch more stable and improve some of the cooking qualities.

If you completely hydrogenate a batch of oil you end up with saturated fat. But if you only partially hydrogenate the batch, you will produce some saturated fats as well as some unsaturated fats with an unusual shape, called trans.

An unsaturated fat normally has a curved, or cis structure (unlike a saturated fat which is straight). But a trans fat is an unsaturated with a structure that is more straight.

When reading food labels, if an ingredient is called “hydrogenated oil,” then it is fully hydrogenated and will contain practically no trans fats. If an oil is listed as “partially hydrogenated” then it will contain trans fats.

The research is clear that trans fats increase LDL cholesterol and lower HDL. They also increase inflammation and harm the walls of blood vessels. The American Heart Association recommends that trans fats be less than 1% of energy intake.

In 2006 a meta-analysis by Mozaffarian et al. (1) was published in the New England Journal of Medicine. It included four prospective studies that calculated the increased risk for coronary heart disease based on substituting 2% of carbohydrate calories with trans fats:

They also looked at three retrospective studies in which those in the top quarter of trans fat levels in their fat tissues were compared to those in the bottom quarter to measure an increased risk of heart disease:

Thus, the findings have been pretty consistent (especially for nutrition studies on fatty acids). I looked for other, more recent studies such as these and did not find any.

Interestingly, the only place where trans fats are found naturally are animal products, where they are produced by bacteria in the gut of ruminant animals. In fact, a trans fats in dairy products, conjugated linoleic acid, is touted for its health benefits and sometimes pointed to by people arguing against veganism as necessary for optimal health. Here is what Mozaffarian et al. say about trans fats from ruminant animals:

[D]ietary trials indicate that consumption of conjugated linolenic* acid reduces insulin sensitivity, increases lipid peroxidation, and has mixed effects on markers of inflammation and immune function. Of four prospective studies evaluating the relation between the intake of trans fatty acids from ruminants and the risk of CHD, none identified a significant positive association, whereas three identified nonsignificant trends toward an inverse association….[T]he sum of the current evidence suggests that the public health implications of consuming trans fats from ruminant products are relatively limited.

*This appears to be a typing error and should say “linoleic” (not “linolenic”). The studies they cite are done on conjugated linoleic acid.

In the USA, a food label is allowed to list the trans fat level as zero if it contains less than .5 g per serving, and apparently many foods listed as zero have close to .5 g. So, it’s best to rely on the ingredients list and avoid foods with “partially hydrogenated oil.”

This entry was posted on Sunday, October 24th, 2010 at 5:09 pm and is filed under Fat, Trans Fats. You can follow any responses to this entry through the RSS 2.0 feed.
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I think that’s a lesson learned from vegan activism, there is a tendency to claim certain health benefits even if the vegan diet is not the healthiest diet but it could still be healthy and many folks won’t care about 85 v. 86 for having a sense of morals and conscience.

Reason being is that a campaigner against saturated fat was partially responsible for trans fat via phil sokolof, although I’m not certain what his diet.

For instance could we then have a debate of eco-atkins claiming that non-eco atkins diets are unhealthy.